Multistage-bleeder-turbine control



y GB\ l Oct.`7, 1930. l R. MARSLAND 1,777,470.

MULTISTAGE BLEEDER TURBINE CONTROL Filed April` 10. 1929 INVENTOR Fs' 2RMnrslnnd ,amm

ATTORNEY Patented Oct. 7, 1930 l UNITED STATES yPA'rENrI OFFICE ROLAND`INIIARSLAND, OF MOYLAN, PENNSYLVANIA, ASSIGNOB TO WESTINGHOUSE ELECTRIC@c MANUFACTURING COMPANY, A CORPORATION F PENNSYLVANIAMULTISTAGE-BLEEDER-TURBINE CONTROL Application filed April 10,

My invention relates to a governing system, more particularly to agoverning or cont-rol system for a double or multiple extractionturbine, and it has for its object to -pro- '5 vide improved regulation.

A specific object is to regulate the flow at each extraction opening inresponse to the pressure of the extracted steam, and to compensate theadmission of motive fluid to the turbinein accordance with the amount ofsteam extracted at each of the extraction openings.

These and other objects areeffected by m e invention, as will beapparent from the fo lowing description and claims taken in connectionwith the accompanying drawin s,

forming a part of thisapplication, in whic Fig. 1 'is a diagrammaticrepresentation vof my governing system; and, 2o

Fig. 2 is a sectional view ofl a detail.

Referring n'ow to the drawing more in detail, I show a turbine 10 havingan admission valve 11, andextraction openings 12 and 13 communicatingwith intermediate pressure stages in the turbine'indicated at 14 and 15,respectively. Diaphragms 16 and 17 are interposed between the pressurestages 14 and 15 and the succeeding turbine stages, and conduits 18 and19'provide by-passes around the diaphragms, through which the motivefluid not extracted may be conveyed to continue its expansion in a lowerpressure stage' or stages of the turbine.

Valves 21 andv 22y are provided in the bypass conduits 18 and 19 tocontrol the flow` of motive fluid therethrough. By controlling theamount of fluid held back'from the lower pressure stages, these valvesregulate the flow throughthe extraction openings 12 and 13. It will beapparent to those skilled in the art that any other construction whichregulates the distribution of fluid between the bleeder opening and thesucceeding turbine stages may be used as the equivalent of the by-passvalve.

The admission valve 11 and the by-pass valves 21 and 22 are controlledby governors 23, 24 and 25, respectively, wh1ch may be and are shown assimilar in construction; Each governor includes a piston 26 operat-1929. Serial No. 854,027.

' The variable lfluid pressure is admitted to the lower end of thecylinder to bias the piston upwardly, and a spring 28 biases the piston26 downwardly in opposition to smid fluid pressure. The iston 26 isyrovided with a restricted ori ce 29, throug y which some of the fluidunderpressure beneath the piston flows tothe upper side of the piston. Aback pressure is imposed on the fluid flowing through the orifice bycontrolling its escapev from the u per end of the cylinder, and thispressure iases the piston 26 in cooperation with the spring 2,8 and inoppos1- tion to the variable fluid pressure beneath the piston.' Eachpiston is connected to its valve in any suitable manner known to theart, as through a fulcrumed lever 31.

The back pressure in the governor 24 is controlled in response topressure at the extraction opening 12, that 1n the governor 25 inresponse to pressure at the opemng 13, and that in the governor 23 inresponse to both` of saidpressures. The mechanism for accomplishing thiswill now be descr1bed. The pressure ofthe fluid flowing through theextraction opening 12 and the condult ling a ever 38 fulcrumedintermediate its ends, as at 39. An adjustable srring 41 biases t-helever 38 in opposition to the diaphragm and gives it a positioncorresponding to the pressure imposed on the dlaphragm 37.

Connected to the lever 38 on the other side of the fulcrum 39 is a stem42 controlling a relief or back-pressure Valve 43. The valve 43communicates4 with the up er end of the cylinder of the governor 24 trough a conduit 44, and controls the pressure therein by controlling theescape of fluid therefrom. Referring now to Fig. 2, the stem 42 extendsthrough the cylindrical valve casing 45 and through a piston 46operating therein.

The piston 46 abuts the upper end of a spring 47, which biases the valve43 to closed position. A passage 48 is formed in the lower end ofthestem 42 andr extends from a point. which is normally just above the topface of the piston 46 to the lower end thereof. A drain conduit 49communicates with the valve. casing between the'piston 46 and'the valve43.

Fluid pressure from y,the impeller 32 is supplied to the valve casing 45above the piston 46 through a conduit 51, in which an orifice 52 isinterposed to restrict the flow to the valve casing. This pressure isim' osed o n the piston 46 and moves the same ownwardly until the upperend of the passage 48 is uncovered suiciently to permit the escape of asmuch fluid as flows into the casing.

When the stem 42 is moved downwardly, the esca e of the fluid flowinginto the casing is cut o and the piston 46 moves downwardly untilthepassage 48 is again slightly luncovered to permit suilicient escape, andwhen the stem moves upwardly, the passage 48 permits a greater amount offluid to escape until the spring 47 moves the piston 46 upwardly torestore' the required escape openlt will thus be seen that the piston 46is moved to follow the stem 42 without any substantial resistance tomovement of the stem, thereby applying a spring pressure on the valve 43in accordance with the position ot the stem 42.

The pressure of the fluid flowing through the extraction opening 13 tothe conduit-53 is communicated tov a similar diaphragm 54, which acts ona lever fulcrumed at 56 and biased by an adjustable spring 57. The oth.-

` er end of the lever 55 actuates a stem 58 controlling a back pressurevalve 59 in the same manner that the stem 42 controls the valve 43. Thevalve 59 communicates through a conduit 61 with the upper end of thecylinder of the governor 25, and controls the back pressure therein.

A floating lever 62 is connected at its'ends to the levers 38 and 55,and intermediate its ends is connected to a link 63. y The link 63, inturn,is connected to a stem 64 by a lever 65 pivoted to a fulcrum at 66.The stem 64 controls, in the manner in which valve 43 is controlled, aback-pressure valve 67, which communicates with the admission valve gov#ernor 23.through a conduit 68'and controls the back pressure therein. Y

The fulcrum 66 is vertically adjustable, by means of a screw-threadedstem 66', tovary the back pressure imposed by the valve 67 relative tothe link 63, thereby controlling the speed setting of the governingsystem.

The operation of this embodiment of my invention is as follows;

The admission valve 11 andthe by-pass valves 21 'and 22 all move inresponse to changes in speed of the turbine by reason of the impellerpressure imposed on the under side of each governor p1ston 26. Upon anincrease in speed, the impeller pressure increases, moving the pistons26 upwardly against the-spring 28 and closing the valves. The flow offluid is thus decreased through the length of the turbine. The pressureat each extraction opening, however, remains substantially the same.

Upon decrease in speed and decrease in fluid pressure, the springs 28move the pistons 26 to increase the valve openings.

The correct extraction pressures are maintained in the following manner:Assume that v the demand for steam from the pressure stage 14 increases,resulting in a decreased pressure. The decreased pressure iscommunicated to the diaphragm 37, permitting the spring 41 to act on thelever 38 to raise the stem 42.. Raising of the stem 42, as explainedabove, causes upward movement of the piston 46, which decreases thecompression of the spring l47 and thereby decreases the back pressurewhich the valve 43 imposes on the fluid escaping from the upper end ofthe cylinder in the governor 24. The impeller pressure below the piston26 in the governor 24 now preponderates and moves thepiston upwardly to*decrease the opening of the by-pass valve 21. 'More fluid 1s thus heldback from the `lower pressure stages to supply the bleeder takes place,as will be apparent, increasing the by-pass valve opening to pass the'excess steam to the lower pressure stages of the turbine.

Changes in bleeder pressure in the conduit 53 are likewise communicatedto the diaphragm 54, moving the lever 55 and the stem 58 to vary theback pressure in the governor 25 and vcontrolling the by-pass valve 22to hold back sufficient steam for bleeder demand.

The changes in bleeder demand at either opening affect the amount ofwork done by the fluid in carrying the turbine load, since, as will beapparent, the fluid extracted does not complete its expansion in thelower pressure stage or stages. sarv to compensate the admission valvefor the amount of fluid extracted through the It is, therefore,necesmovement of the lever 62 results in upward movement of the link 63and downward i movement of the stem 64. The spring 47 is further comressed and the valve 67 imposes an increase back' pressure, whlch 1scommunicated to the governor 23. The piston 26 is, therefore, moveddownwardly to increase the. admission valve opening. Addi- Itional-motive fluid is thus supplied to carry the turbine load and tosupply a part of the increased demand for steam at the extractionopening 12.

Upon decrease 1n demand for extraction steam, the reverse operationtaken place.

Upon an increase 1n demand for extractlon -steam at the opening 13, thepressure'drops,

and, as explained above', the end of the lever to which the stem 58 andthe lever 62 are connected, is moved upwardly` moving the lever (S2-andthe stem 63 upwardly. The admission valve opcning is increased, asbefore explained, thus admitting more steam to compensate for theincreased amount of bleedlng.

It will thus be seen that. I have devised a novel fluid pressuregoverning system for a multiple extraction turbine wherein the admissionvalve governor is compensated for the amount of partially expanded steamextracted from the turbine at a plurality of pressure stages.

' While I have shown my invention in but one form. it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof yvarious changes and modifica-y extraction at two of said openingsand means responsive to said `Huid pressure for controlling theadmission valve.

2. The combination with a turbine having an admission valve and aplurality of extraction openings, of governing means" for the admissionvalve comprising means providing` a fluid pressure varying in accordancewith the extraction at two of said openlngs and means responsive to saidfluid pressure and to speed of the turbine for controlling the admissionvalve.

3. The combination with a turbine having an admission valve and aplurality of extraction openings, of governing` means for the admissionvalve comprising means providing a iiuid pressure varying in accordancewith the extraction at two of said openings, means providing'a fluidpressure varying as a function of the speed. the turbine, and

means responsive to bothof said fluid pres sures for controlling saidadmission valve.

4. The combination with an elastic uid turbine havin an admission valveyand o eninvs communicating with two' interme iate pressure stagestherein, of means providing ak fluid pressure variable in response tothe pressures at both of said pressure stages, and means responsive tosaid variable fluid pressure and to the speed of the turbine forcontrolling said admission valve.

5. lThe combination with an elastic uid turbine having an admissionvalve and openings communicating with a plurality of pressure sta-gestherein, of a governing system therefor including means associated witheach of said openings for controlling the flow of fluid therethrough inaccordance with the pressure thereof, means providing a luid pressurevarying with the pressures at a plurality of said openings, and meansresponsive to said variable fluid pressure forcontrolling said admissionvalve.

6. The`combination with an elastic fluid turbine having an admissionvalve and openings communicating with two pressure stages therein, of agoverning system therefor comat each of said openings in response to thepressure thereof, means `providing a fluid pressure variable in responseto the Ypressures at both of said pressure stages, and means responsiveto said variable :fluid pressure and to the speed of the turbine forcontrolling said admission valve.

7. The combinationwith a turbine having openings communicating with aplurality of pressure stages therein, a valve regulating the flow offluid at each of said stages and an admission valve, of meanscontrolling the valve at each stage in response to the pressure thereinand to the speed of the` turbine, means providing a fluid pressurevarying in response to the pressures in a plurality of said stages, anda governor responsive to the speed of the turbine and to said variableiluid pressure for controlling the admission valve.

8. The combination with an elastic fluid turbine having an admissionvalve and o nings communicating with two interme iate pressure stagestherein, of a governing system prising means for regulating the flow offluid los therefor comprising meansl associated with each of saidpressure stages for providing a fluid pressure varying in response tothe pressure at the pressure stage and regulating the flow of Huid atthe pressure stage in response to said variable fluid pressure,means-operated b both of said means and providing a variab e vfluidpressure, and means responsive to said last-mentioned Ifluid pressurefor controlling said admission valv l 9. The -combination with anelastic fluid turbine having an admission valve and openingscommunicating with two intermediate pressure stages therein, of agoverning systern therefor 'comprising means associated with each ofsaid pressure stages for providing a fluid pressure varying in responseto the pressure at the pressure stage and for regulating the flow offluid at the pressure stage in response to said variable fluid pressure,means operated by both of said means and providing a variable Huidpressure, and means responsive to said last-mentioned fluid Y pressureand to the speed of the turbine for controlling said admission valve.

10. The combination with a turbine having a plurality of extractionopenin an admission valve, and a valve regulatmg the flow at each ofsaid openings, of means for controllinglsaid valves comprising meansproviding a Huid pressure varying as a function of the speed of theturbine, a governor for each valve,.each governor having apressureresponsive element subjected to said uid pressure, meansassociated with each extraction opening providing a fluid pressurevarying wlth the pressure of the extracted fluid,

means for subjecting said variable fluid pressure to thepressure-responsive elements of the associated governor, means providinga Huid pressure varyingwith the pressures of the extracted uid ata'plurality of saidI extraction openings, and means for applying saidlastmentioned fluid pressure to the pressure-responsive element in theadmission valve governor.

In testimony whereof, I have hereunto 'subscribed my name this 27 th daof March, 1929.

ROLAND ARSLAND.

